This invention relates generally to a capacitive differential pressure sensor and method using the same at oil or gas wells.
Differential pressures can be measured by linearly variable differential transducers or strain gauges. These instruments typically are large and have maximum static pressure ratings on the order of 5,000 pounds per square inch (psi). The ones we are aware of are capable of measuring pressure differentials on the order of 50 psi with an accuracy of .+-.1 percent. We are also aware of a capacitive differential pressure transducer using a semiconductor diaphragm between two glass end pieces (see U.S. Pat. No. 4,996,627 to Zias et al.). Although these devices can measure pressure differentials, there is the need for an improved sensor and method of sensing that can be used in the high pressure, high temperature environments found at oil or gas wells.